Karl alqtjist



Jan. 23, 1923.

K. ALQUIST. MARINE PRQPELLERBRAKE. FILED MAR: 19, I920.

a New York, in the county of New Patented Jan. 23, 1923.

.hATEhl @FFHQE.

KARL ALQUIST, 0F NEW YORK, N. Y.

MARINE PROPELLER BRAKE.

Application filed March 19, 1920. Serial No. 367,157.

To all whom it may concern:

Be it known that I, KARL ALQUIST, a subject of the King of Sweden, residin at fork, State of New York, have invented certain new and useful Improvements in Marine Propeller Brakes, of which the following is a specification.

The present invention relates to marine propulsion and more particularly to the transmission of power from a prime mover to the propeller shaft of a vessel through spur gearing.

It is now known that in a rough sea the power thus transmitted is subject to wide variations, the period of the variations be ing substantially dependent upon the pitch ing of the vessel. The prime mover generally a steam turbine, revolving at a high speed, has a comparatively large fly wheel capacity while the propeller with its shaft and the driven portion of the gear, have a small fly wheel capacity. In the case of a double reduction gearin the prime mover and high speed end of t e gearing may be considered a high speed system and the propeller and low speed end of the gearing a low speed system. The body of water in I which the propeller rotates will, due to the action of the waves, periodically vary its speed relatively to the ship in the direction of motion of the ship and it thus may happen that at times the propeller, instead of being driven by the gear, is driven by the water. When this happens, the prime mover referred to will speed up the system, but in a heavy sea it may happen that the propeller is accelerated by the water at a higher rate than that of the prime mover, due to the unequal flywheel efli'ects of the two ends of the system before referred to. In such a case, the normal driving portion of the gear will be driven, resulting in a shifting of the teeth in mesh through the clearance space to contact on the other sides of the teeth. The continuity of the driving pressure and contact .is thus broken and when the normal direction of drive is reestablished, i e. when the propeller hits the water again, there results a large temporarily increased pressure 'on the gear teeth due to the speeding up of the system durlng the period described, and this pressure is further increased by a blow between the merit in substance comprises load means teeth. Also when the inion does not drive, it generally moves enc wise from its normal pos tion and, when the drive comes on, will oscillate with blows before steadying down. It is evident that the increase in pressure between the gear teeth due to the blows, is substantial, and as the life of the gear is dependent on keeping down their maximum pressure peaks as far as possible, the importance of maintaining the continuity of drive and avoiding such blows is apparent.

The object of my invention is to provide an improved structure and arrangement in a marine propulsion system which will overcome the above difliculties, and for a consideration of what I believe to be novel and my invent-ion attention is directed to the following description and the claims appended thereto.

According to my invention I maintain the continuity of pressure by increasing the resistance to acceleration of the driven or low speed element or elements of the system, i. e., the part of the system mounted on the propeller. shafting, so that the rate of acceleration, even for the most unfavorable conditions of sea, lies below the rate of acceleration of the driving or high speed system when the load is lost. To this end, I provide on the low speed system a brake which can be intermittently applied. This brake may be mechanical, consisting of a wheel or disk on the propeller shaft and means for applying retarding or braking forces to this wheel or disk. It may also be electrical. In this latter connection I may, for instance, provide on or connected with the propeller shaft, a generator which is electrically connected to drive motors mounted in connection with the high speed system. In such case, only a small portion of the power will be wasted. The arrangeor effecting the application of a pressure between the teeth of the driving and the driven elements of the gear, which is independent of the external load. For simplicity, this pressure may be left on during the complete cycle of variations, i. e., during the whole time the roughness of the sea makes this desirable as it will not be a large percentage of the normal load. When no longer required, this extra pressure may be removed by opening a switch to break the circuit between the generator and motors and thus letting them run idle. In the case of a meehanicarbrake, asabove referred to, it is preferable however to" apply the brake only when the propeller is driven by the sea. In such a case, there is a negative torque in the propeller shaft, and the pressure on the thrust block is also reversed and this change of conditions may be used for applying the brake as well as for releasing it when normal conditions are restored.

' In the di'awingiFig. 1 is a View of a more or less diagrammatic nature, illustrating. an embodiment of my invention; and Figs. 2 and '3 are similar views of modifications.

Referring to the drawing, in each of Figs. 1, 2 and 3, 5 indicatesa propeller shaft drive rdirectly by a low speed gear wheel 6 which in turnis indicated as being driven bytwo low speed pinions 7. This may be considered as constituting the low speed end cfa double reduction gearing, the high speed end of which may comprise a high speed pinion driving two high speed gear wheels on the same shafts as are pinion's 7 which shafts are termed the intermediate speed shafts. At 8 is indicated an ordinary axially flexible cushioning thrust beariiig for propeller shaft 5.

In connection with Fig. 1, I have inclicated the high spee'd end of the gearing as comprising a pinion 3O meshing with two gear wheels 31 and 32 on the intermediate speedshafts. These are preferably double helical gears, only one-half of the gears being shown. indicates an elastic iiuid turbin e for driving pinion 30.

Now, according to my invention as shown inFi 1, I mount a fixed brake disk 10 on prop ller shaft 5, and adjacent its braking surface, indicated at, 11, I provide a station ary ring 12 having a braking surface adapted to be engaged by braking surface 11. Ring 12 is carried by a fixedsupport or other suitable means, as indicated at 13, and is adjustable toward and away from disk 10 by meaiis of bolts 14 and springs 15. With this arrangement when there is, a movement of the propeller shaft toward the stern,i. e. toward the left, when the thrust is reversed on the thrust block 8, as before described, brake disk 10 will move into engagement with ring 12, thereby applying a friction load to the propeller shaft. Springs 15 serve tolimit the amount of the friction braking action.

In Fig. 2 is shown an arrangement similar to Fig. 1, except that a greater relative movement "of the brake members towards each other is effected. In this arrangement, brake disk 10 and stationary ring 12 are mounted adjacent each other as are disk 10 and ring 12 of Fig. 1. Ring 12* is supported from a fixed support 13? by means of rods 16, there being springs 17 between heads 18 of rods 16 and ring 12", and springs 19 between rings 12 and support 13. Connected to each rod 16 isa lever 20 fulcrumed at21 and hearing at one end against the thrust block 8. With this arrangement when there is a movement of the propeller shaft toward the stern when the thrust is reversed, not only will brake disk 10 be moved toward ring 12 but also ring 12 will be pulled toward disk 10 due to levers 20 which are moved by the move ment of the thrust block in a direction to pull on rods 16 in a direction to move ring 12? toward disk 10*. As is well understood. a thrust bleck is almost unavoidably not rigidly supported in the ship, so that whenever the forward pressure on it is released it will spring back ,t little, a feature which is embodied in this particular thrust block, so that normally unfiexed it will maintain the brake in action. The springs'l? serve to limit the amount of the brakejpressure, while the springs 19, which are much weaker than springs 17, serve to move ring 12 away from disk 1O when the pressure is relieved.

' In the form of my invention shown in Fig. 3, I provide a generator 25 on the propeller shaft which is connected'to drive niotors 26 on the intermediate speedshafts which carry low speed-pinions-7. Generator 25' may be connected permanently through suitable switches to motors 26 under which circumstances serves to supply always a load onthe propeller shaft 5; or the ar -rangement may be such that the end movement of the propeller shaft may be utilized to close afswitch to connect the'generator to the motors. a combination ofv the two arrangements may be usedwhereby in rough weather the generator may be permanently connected to the motors while in'. smooth weather the generator may be connected to the motors only in caseaoreversal of thrust on thepropeller shaft occurs In the draw ing, a diagrammatic circuit arrangement is shown byway of example. '27 is. a switch lever. adapted to be brought intoengagement with contacts 28 bya movement of: the propeller shaft toward the left and, asis obvious, when in engagement, generator 25, is connected to motors 26. By closing a manually operated switch 29, generator. 25 may be permanently connectedto motor 26; The arrangement of Fig. 3, it will be clear, forms in substance a magnetic braking arrangement for the propeller shaft which may; be varied to obtain the proper effect by varying the field strength of the motors or generator.

In calm weather or whentheshipimoves backward, the brakemay be thrown out of operation, electrically as inFig. 3, by opening the generator circuit or. mechanically by moving the ring.12. ot Fig. 1 and ri1r1g12; of Fig. 2, eachwith its attached-and related members, backward axially a short distance.

i In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. In combination, a propeller shaft, a gearing for driving it, an axially flexible, cushioning thrust block for the propeller shaft, and means actuated by axial movements of the propeller shaft and thrust block due to decrease in the axial thrust for applying a braking load to the propeller shaft.

2. In combination, a propeller shaft, a gearing for driving it, an axially flexible, cushioning thrust block for the propeller shaft, a brake for the propeller shaft, and a lever actuated by axial movements of the propeller shaft and thrust block due to decrease in the axial thrust for applying said brake In witness whereof, I have hereunto set my hand this tenth day of March 1920.

KARL ALQUIST. 

